Constant-speed cruise control device for a vehicle

Abstract

When an IDLE switch goes on and so a condition of strong possibility of fuel cutoff is obtained, a throttle degree of opening is immediately opened slightly and an IDLE switch goes off, and thereby actual entry of an electronic-control fuel-injection device into fuel cutoff processing can be prevented. Moreover regulation of the throttle degree of opening to a closed side is blunted by enlargement of an insensitive zone of a difference between target cruising speed and vehicle speed, and so the throttle degree of opening does not change and a rise of vehicle speed Vn continues for a while. Because of this, a large cycle of vehicle change is repeated and so physical sensations do not deteriorate.

What is claimed is: 
     
       1. A constant-speed cruise control device for a vehicle provided with a fuel cutoff control device to stop fuel supply to an internal combustion engine in a case where a fuel cutoff condition has been obtained, said constant-speed cruise control device comprising: vehicle speed detecting means for detecting a vehicle speed of a vehicle;   drive power regulating means, connected to said vehicle speed detecting means, for regulating drive power of said internal combustion engine to cause vehicle speed to match a target cruising speed and a comparative speed based on the vehicle speed detected by said vehicle speed detecting means during constant-speed cruise control;   fuel cutoff condition detecting means for detecting when at least one of a fuel cutoff condition and a condition wherein a possibility of fuel cutoff is strong has been obtained, said fuel cutoff condition detecting means being a switch, said switch assuming a first state under a condition when the possibility of fuel cutoff is strong and a condition when fuel cutoff occurs, said switch assuming a second state when the possibility of fuel cutoff is weak; and   increasing means, connected to said fuel cutoff condition detecting means and responsive thereto, for increasing drive power of said internal combustion engine to avoid execution of said fuel cutoff control by said fuel cutoff control device when, during constant-speed cruise control, said switch assumes said first state.   
     
     
       2. A constant-speed cruise control device for a vehicle according to claim 1, wherein said drive power regulating means is further for driving a throttle of said internal combustion engine and regulates drive power of said internal combustion engine by regulating a throttle degree of opening of said internal combustion engine. 
     
     
       3. A constant-speed cruise control device for a vehicle according to claim 2, wherein said fuel cutoff condition detecting means is further for driving said throttle and detects that said fuel cutoff condition has been obtained when said throttle degree of opening approaches zero. 
     
     
       4. A constant-speed cruise control device for a vehicle according to claim 1, wherein said drive power regulating means stops regulating said drive power of said internal combustion engine when an absolute value of said difference between said comparative speed and said target cruising speed is lower than a predetermined value. 
     
     
       5. A constant-speed cruise control device for a vehicle according to claim 4, further comprising changing means, connected to said increasing means, for changing said predetermined value so that a limit where said drive power regulating means stops regulating said drive power is enlarged after said increasing means increases said drive power. 
     
     
       6. A constant-speed cruise control device for a vehicle according to claim 5, wherein said changing means is connected to said vehicle speed detecting means and is further for changing said predetermined value only when said comparative speed is higher than said target cruising speed. 
     
     
       7. A constant-speed cruise control device for a vehicle according to claim 5, wherein said changing means is connected to said vehicle speed detecting means and is further for changing said predetermined value only when said comparative speed is lower than said target cruising speed. 
     
     
       8. A constant-speed cruise control device for a vehicle according to claim 1, wherein said increasing means is further for driving a throttle of said internal combustion engine and increases said drive power by increasing said throttle degree of opening. 
     
     
       9. A constant-speed cruise control device for a vehicle according to claim 1, wherein said increasing means is implemented using a microprocessor. 
     
     
       10. A constant-speed cruise control device for a vehicle provided with a fuel cutoff control device to stop fuel supply to an internal combustion engine in a case where a fuel cutoff condition has been obtained, said constant-speed cruise control device comprising: vehicle speed detecting means for detecting a vehicle speed of said vehicle;   drive power regulating means, connected to said vehicle speed detecting means, for regulating drive power of said internal combustion engine to cause the vehicle speed to match a target cruising speed based on a difference between the target cruising speed and a comparative speed based on the vehicle speed detected by said vehicle speed detecting means during constant-speed cruise control;   fuel cutoff condition detecting means for detecting when at least one of a fuel cutoff condition and a condition wherein a possibility of fuel cutoff is strong has been obtained, said detecting means assuming a first state under a condition when the possibility of fuel cutoff is strong and a condition when fuel cutoff occurs, said detecting means assuming a second state when the possibility of fuel cuttoff is weak;   stopping means, connected to said drive power regulating means, for stopping regulation of said drive power by said drive power regulating means when an absolute value of said difference is a predetermined value or less; and   changing means, connected to both said stopping means and said fuel cutoff condition detecting means and responsive to said detecting means, for changing said predetermined value so that a limit where said drive power regulating means stops regulating said drive power is enlarged when said fuel cutoff condition detecting means during constant-speed cruise control assumes said first state.   
     
     
       11. A constant-speed cruise control device for a vehicle according to claim 10, wherein said changing means changes said predetermined value only when said comparative speed is higher than said target cruising speed. 
     
     
       12. A constant-speed cruise control device for a vehicle according to claim 10, wherein said changing means changes said predetermined value only when said comparative speed is lower than said target cruising speed. 
     
     
       13. A constant-speed cruise control device for a vehicle according to claim 10, wherein said changing means changes said predetermined value on both sides where said comparative speed is larger and smaller than said target cruising speed. 
     
     
       14. A constant-speed cruise control device for a vehicle according to claim 10, wherein said drive power regulating means regulates said drive power of said internal combustion engine by regulating a throttle degree of opening of said internal combustion engine, and said fuel cutoff condition detecting means detects that said fuel cutoff condition has been obtained when said throttle degree of opening approaches zero. 
     
     
       15. A constant-speed cruise control device for a vehicle according to claim 10, wherein said drive power regulating means regulates said drive power of said internal combustion engine by at least one of a regulated quantity and a regulated speed determined from said difference based on a map established previously to indicate a relationship between said difference and at least one of a regulated quantity and a regulated speed; and said changing means for changing said predetermined value by replacing said map to another map.   
     
     
       16. A constant-speed cruise control device for a vehicle provided with a fuel cutoff control device to stop fuel supply to an internal combustion engine in a case where a fuel cutoff condition has been obtained, said constant-speed cruise control device comprising: vehicle speed detecting means for detecting a vehicle speed of a vehicle;   drive power regulating means, connected to said vehicle speed detecting means, for regulating drive power of said internal combustion engine to cause vehicle speed to match a target cruising speed and a comparative speed based on the vehicle speed detected by said vehicle speed detecting means during constant-speed cruise control;   fuel cutoff condition detecting means for detecting when at least one of a fuel cutoff condition and a condition wherein a possibility of fuel cutoff is strong has been obtained, said fuel cutoff condition detecting means being a switch, said switch assuming a first state under a condition when the possibility of fuel cutoff is strong and a condition when fuel cutoff occurs, said switch assuming a second state when the possibility of fuel cutoff is weak; and   increasing means, connected to said fuel cutoff condition detecting means and responsive thereto, for increasing drive power of said internal combustion engine to avoid execution of said fuel cutoff control by said fuel cutoff control device when, during constant-speed cruise control, said switch assumes said first state;   wherein said drive power regulating means stop regulating said drive power of said internal combustion engine when an absolute value of said difference between said comparative speed and said target cruising speed is lower than a predetermined value; and   said constant-speed cruise control device further comprises changing means, connected to said increasing means, for changing said predetermined value so that a limit where said drive power regulating means stops regulating said drive power is enlarged after said increasing means increases said drive power.   
     
     
       17. A constant-speed cruise control device for a vehicle provided with a fuel cutoff control device to stop fuel supply to an internal combustion engine in a case where a fuel cutoff condition has been obtained, said constant-speed cruise control device comprising: vehicle speed detecting means for detecting a vehicle speed of a vehicle;   drive power regulating means, connected to said vehicle speed detecting means, for regulating drive power of said internal combustion engine so as to cause vehicle speed to match a target cruising speed based on a difference between the target cruising speed and a comparative speed based on the vehicle speed detected by said vehicle speed detecting means during constant-speed cruise control;   fuel cutoff condition detecting means for detecting when at least one of a fuel cutoff condition and a condition wherein a possibility of fuel cutoff is strong has been obtained, said detecting means assuming a first state under a condition when the possibility of fuel cutoff is strong and a condition when fuel cutoff occurs, said detecting means assuming a second state when the possibility of fuel cutoff is weak;   increasing means, connected to said fuel cutoff condition detecting means and responsive to said detecting means, for increasing drive power of said internal combustion engine to avoid execution of said fuel cutoff control by said fuel cutoff control device when said fuel cutoff condition detecting means during constant-speed cruise control assumes said first state,   wherein said drive power regulating means stops regulating said drive power of said internal combustion engine when an absolute value of said difference between said comparative speed and said target cruising speed is lower than a predetermined value, and   changing means connected to said increasing means, for changing said predetermined value so that a limit where said drive power regulating means stops regulating said drive power is enlarged after said increasing means increases said drive power, and   wherein said changing means is connected to said vehicle speed detecting means and operates to change said predetermined value only when said comparative speed is higher than said target cruising speed.   
     
     
       18. A constant-speed cruise control device for a vehicle provided with a fuel cutoff control device to stop fuel supply to an internal combustion engine in a case where a fuel cutoff condition has been obtained, said constant-speed cruise control device comprising drive power regulating means for regulating drive power of said internal combustion engine so as to cause vehicle speed to match a target cruising speed based on a difference between the target cruising speed and a comparative speed based on the vehicle speed detected by said vehicle speed detecting means during constant-speed cruise control; fuel cutoff condition detecting means for detecting when at least one of a fuel cutoff condition and a condition wherein a possibility of fuel cutoff is strong has been obtained, said detecting means assuming a first state under a condition when the possibility of fuel cutoff is strong and a condition when fuel cutoff occurs, said detecting means assuming a second state when the possibility of fuel cutoff is weak;   increasing means connected to said fuel cutoff condition detecting means and responsive to said detecting means, for increasing drive power of said internal combustion engine to avoid execution of said fuel cutoff control by said fuel cutoff control device when said fuel cutoff condition detecting means during constant-speed cruise control assumes said first state,   wherein said drive power regulating means stops regulating said drive power of said internal combustion engine when an absolute value of said difference between said comparative speed and said target cruising sped is lower than a predetermined value, and   changing means connected to said increasing means for changing said predetermined value so that a limit where said drive power regulating means stops regulating said drive power is enlarged after said increasing means increases said drive power,   wherein said changing means is connected to said vehicle speed detecting means and operates to change said predetermined value only when said comparative speed is lower than said target cruising speed.